Biological Magnification How harmful toxins can spread through an ecosystem doing damage to each level of the food chain

Energy Pyramid Review Autotrophs can produce their own food and make up the base of the food pyramid. Heterotrophs need to eat other organisms to obtain energy and the building blocks for growth. Since energy is lost at each level of the food chain, there must be a greater abundance of organisms at the bottom of the food chain to support the organisms at the top of the food chain. The organisms at the top of the food chain must eat many organisms from the bottom to sustain themselves.

Biological Magnification The concentration of harmful substances increases in organisms at higher trophic levels on the food chain. So, if we release a chemical or toxin into the environment, the plants might take this chemical up through their roots. The plants then contain a low level of toxin. Then an herbivore eats many of those plants, so the herbivore contains a moderate level of toxins. Then a carnivore eats many of the herbivores, and in turn will contain a high level of the toxins.

Bald Eagles and DDT Farmers used to use a pesticide called DDT. DDT seemed safe and killed insects effectively, but was not biodegradable. When it rained, DDT would be washed into local bodies of water. Algae and other aquatic plants picked up the DDT. Fish ate these algae, and ate lots of it over their life time, so they contained higher levels of DDT. The birds that ate the many fish over their lifetime, such as bald eagles, ospreys, and brown pelicans eventually contained extremely high levels of DDT.

Bald Eagles The DDT infected the entire food chain, but the top carnivores had the biggest impact. The DDT in the birds caused the shells of their eggs to become weaker. When the mother birds sat of the eggs to keep them warm, they would break. Many baby bald eagles dies, which is why they are now an endangered species, and why we no longer use DDT

Humans Where are humans in the food chain? So, how do you think biological magnification affects us? At the top!!! Just like other top predators, we feel the affects more

Humans and Mercury You already know that pregnant women are not supposed to eat fish. This is because of biological magnification. We used to use mercury in many different household items (thermometers, light bulbs, etc.) When we throw these items away they go to a land fill. When it rains, the mercury is washed into our waterways. Algae take up the mercury, fish eat the algae, we catch and eat the fish.

Humans and Mercury Mercury will cause neurological disorders in a developing fetus. They will have issues with memory, cognitive thinking, attention, motor skills, and more. Adults exposed to mercury can develop mad hatter syndrome (like the crazy character from Alice in Wonderland) This impairs the senses and coordination, causes emotional disturbance, and diarrhea.